An automobile normally protects the passengers best during collisions from the front or the rear since the deformation paths and/or crumple zones are relatively long. It is therefore important that passenger protection during side collisions should be improved, such improvement occurring for example by the use of air or other gas-filled cushions which are more generally termed "air bags".
There are many known air bag systems designed to offer protection during side collisions, but none of these however offers a satisfactory solution to the problem of providing a adequately effective side collision protection system.
For instance, there are systems having the air bag placed in the door and which cooperate with an electronic sensor system. But these systems suffer from the disadvantage that it is difficult to achieve correct adjustment and adequate protection against damage. Furthermore a diagnosis system is required for regular control of the electrical system and the air bag has to be relatively large in order to cover all the possible adjustment positions of the vehicle seat, i.e with respect to the adjustability in the longitudinal and height directions and with respect to the back rest's inclination.
The document GB-A-2 255 535 shows a further arrangement whereby an air bag is placed in the door and connected with a pyrotechnic sensor system. This system is simpler since no electrical system is required, but otherwise presents the same disadvantages as in the aforementioned system which means that the door panel will be complicated and the compartment is more limited as regard the inclusion of strengthening members, beams etc.
GB-A-2 232 936 discloses an air bag in the vehicle seat with a sensor located in the door. The advantage with this system is that the bag is always located in the correct position with respect to the passenger, but the disadvantage is however that the signal transmission from the door to the adjustable seat is complicated and vulnerable.